Loss of control

On 16 December 1988, at approximately 1015 hours a Mitsubishi MU-2B60 Marquise aircraft crashed on a Pastoral property 55 km WNW of Leonora Airfield, Western Australia. The pilot and nine passengers were killed, and the aircraft was destroyed by the impact and a subsequent fire.

The report concludes that the aircraft probably accrued icing on the frame which caused the airspeed to decrease to the point where the aircraft stalled and entered a spin; and that the pilot did not become aware of the decreasing airspeed in time to take action to prevent loss of control.

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On 26 January 1990 at 0105 hours, a Mitsubishi MU-28-60 Marquise aircraft crashed approximately 10 km NNE of Meekatharra, WA. The pilot and passenger were both killed, and the aircraft was destroyed by impact and a subsequent fire.

The report concludes that the aircraft probably accrued icing on the airframe which caused the airspeed to decrease to the point where the aircraft stalled and entered a spin; that the pilot was not previously aware of the ice formation; and that he did not take action to prevent the aircraft's speed from decreasing.

On 30 June 2010, a Cessna Aircraft Company 172H (C172), registered VH-RZV, with one pilot on board, was engaged in cattle spotting, about 21 km NNW of Cunnamulla, Queensland (Qld.).

While orbiting a water trough at about 500 ft, the pilot lost control of the aircraft. Damage to the aircraft was consistent with the right-wing colliding with a tree branch, followed by the aircraft impacting the ground inverted, with a steep nose-down attitude

The pilot sustained serious injuries, and the aircraft was severely damaged. The pilot reported that the most likely reason for the accident was an inadvertent stall. This probably occurred while the pilot was performing a steep turn, with his attention divided between flying the aircraft and looking for cattle.

Most stall/spin accidents occur when a pilot is momentarily distracted from the primary task of flying the aircraft. This accident highlights that even an experienced pilot performing a familiar task can be momentarily distracted, resulting in the loss of control of the aircraft.

On 12 May 2010, an instructor and student were conducting circuit training in an Eagle Aircraft Australia X-TS 150 aircraft, registered VH-FPP, at Jandakot Aerodrome, Western Australia. Soon after lift-off the engine started to run rough and lost power. The instructor took over control and, maintaining between 50 and 100 ft above ground level, turned the aircraft towards another runway. Near the end of that runway the aircraft pitched nose-up, stalled and collided with the ground, seriously damaging the aircraft and injuring the occupants.

There was no evidence found of an aircraft defect or anomaly likely to have significantly affected engine power. The investigation found that the decision by the instructor to turn downwind significantly increased the aircraft's energy and therefore the risk of aircraft damage and occupant injury in the case of a forced landing.

Preliminary report released 20 May 2010

On 28 March 2010, a Piper Aircraft Corp PA-30 Twin Comanche, registered VH-KDS, departed from Jandakot Aerodrome, Western Australia for a private flight under the visual flight rules. On board were two qualified pilots, both of whom were endorsed on the aircraft type. Following the failure of the aircraft to return to Jandakot later that day, a search was initiated to locate the aircraft and occupants. The following morning, the seriously-damaged aircraft was located and both occupants were found to have received fatal injuries.

Examination of onboard GPS information indicated that, while tracking towards Jandakot Aerodrome, the aircraft commenced a steep descent from about 3,500 ft above mean sea level that continued to ground level.

Preliminary report released 19 May 2010

On 22 March 2010, at 1009 Central Standard Time, an Embraer - Empresa Brasileira de Aeronautica EMB-120ER Brasilia with two crew, prepared to take off on a training flight from runway 29 at Darwin Aerodrome, Northern Territory. The crew were the only occupants. The training captain advised the aerodrome controller that the departure would incorporate asymmetric flight (simulated engine failure) and was approved by the controller to perform the manoeuvre.

After becoming airborne, witnesses reported seeing the aircraft roll and diverge left from its take-off path. They watched as the aircraft continued rolling left and entered a steep nose-down attitude. It disappeared into trees, south of the runway threshold from where a column of black smoke was seen shortly afterwards.

Aerodrome rescue and firefighting services were in attendance very shortly thereafter and extinguished the fire. Both pilots were fatally injured, and the aircraft was seriously damaged due to impact forces and an intense post-impact fire.

The aircraft was observed shortly after it had taken off towards the south-east, flying at a very low height along the beach towards the Tangalooma resort. The aircraft flew over the resort area and was seen by witnesses to perform a steep climbing manoeuvre. The aircraft then descended steeply, dived into the water whilst heading in a westerly direction away from the resort, and sank.

The aircraft appeared to be operating normally prior to the accident. There was no physiological or mechanical evidence found which may have contributed to the development of the accident. No defect was found which may have precluded normal engine operation; however, the engine appears to have not been delivering power at the time of impact.

The prevailing wind at the time of the accident was a strong south-easterly which is known to cause mechanical turbulence in the lee of the island. This may have affected the pilot's ability to recover from the manoeuvre under the circumstances.

The investigation did not reveal any reason for the unusually low flight path and manoeuvre immediately prior to the accident. The engine could not be functionally tested because of impact damage.

Significant factor

The following factor was considered relevant to the development of the accident: The pilot attempted a manoeuvre at a height from which safe recovery could not be effected.

CIRCUMSTANCES

On arrival at Sydney, the helicopter landed near the helipad and ground- taxied to the concrete apron in the general aviation parking area. The pilot intended to park in a confined space, adjacent to buildings and hangars on the north-eastern extremity of the apron. A number of aircraft were parked in close proximity to the west and south of the intended parking position. A grassed area to the east was free of obstacles. Ground marshalling assistance was not available. The surface wind was from the south-east at 10-15 kts.

The helicopter taxied to the intended parking position and stopped on an easterly heading. Witness evidence concerning the events which followed was not consistent. The pilot reported sensing a rocking motion which he interpreted as the onset of ground resonance. The helicopter was lifted off and turned towards the building. During this manoeuvre, an extreme vibration commenced which caused the pilot to experience a loss of vision and led to a loss of control of the helicopter. The passenger later recalled that the helicopter completed a 180 degree turn on the ground onto a westerly heading before the rocking motion was felt and the pilot lifted the helicopter off the ground. A ground witness seated inside the building observed the helicopter come to a halt on an easterly heading. It then became airborne and completed a hover turn left onto a westerly heading, at a height of approximately 8-10 feet. As the helicopter settled momentarily, it appeared to be rocking slightly and touched down on each wheel individually, suggesting the pilot was experiencing minor control difficulties.

The helicopter became airborne a second time and was observed to turn right onto a northerly heading, facing a building adjacent to the apron. Severe pitching oscillations commenced as the helicopter climbed to a height of about 30 ft. After several oscillations, the helicopter yawed and rolled to the left, travelling in a westerly direction towards a parked Learjet. The angle of bank increased to 90 degrees and the nose began to drop at about the time the main rotor blades struck the tailplane of the Learjet and the concrete apron. Debris was scattered over a wide area. The fuselage was propelled forward such that the nose of the helicopter collided with the closed doors of a hangar. The helicopter then impacted heavily with the apron on its left side. The tail boom separated and the extensively damaged fuselage came to rest lying on its left side, with the left engine continuing to run.

An extensive technical investigation, which was hampered by the degree of impact damage, did not reveal any evidence of a pre-existing mechanical fault or defect. The investigation was unable to positively establish the reasons for the oscillations reported by the pilot as being the onset of ground resonance, or the source of the extreme vibration which caused the pilot to lose vision and control of the helicopter. However, it was noted that the helicopter was operated in close proximity to a building in wind conditions which favoured recirculation of airflow through the main rotor disc. A possible source of vibration was the interaction of main rotor downwash and the tail rotor . It was also noted that the helicopter was taxied into a confined area where the manoeuvring options available to the pilot were limited.

SIGNIFICANT FACTORS

The following factors were considered relevant to the development of the accident:

1. The helicopter was ground-taxied to a parking position which was in close proximity to buildings and hangars.

2. The parking position and the wind conditions were conducive to the onset of main rotor recirculation.

3. The pilot reported the suspected onset of ground resonance.

4. During an attempt to recover from suspected ground resonance, an extreme vibration developed which led to the loss of control of the helicopter.

On 25 November 2009, an Ayres Corporation S2RT341 aircraft, registered VH-NZB (Figure 1), was being operated on a ferry flight from Parkes, New South Wales (NSW) to Batchelor, Northern Territory (NT), with an initial intermediate stop at Longreach, Queensland (Qld). While on final approach to Longreach, without warning, the aircraft's nose pitched upward, and an aerodynamic stall resulted. The pilot, the sole occupant, regained control and the aircraft landed safely.

A subsequent engineering investigation by the aircraft's maintenance provider determined that the elevator push rods had been fitted in the reverse order during recent maintenance, thus restricting the amount of nose down elevator travel available to the pilot.

The maintenance organisation advised the ATSB that, as a result of this occurrence, it has initiated a number of safety actions, including:

• exploring options for modifying the design of the bellcrank assembly to ensure that the push rods can only be fitted in the correct position
• ensuring that all employees are aware of their responsibilities when conducting dual maintenance inspections on flight control systems.

Preliminary report released 25 January 2010

At about 0800 Western Standard Time on 17 November 2009, the pilot of a Cessna Aircraft Company A188B Agwagon was fatally injured when his aircraft impacted terrain while conducting spraying operations near Kojonup, WA. The aircraft was destroyed.

Interim factual report released 3 December 2008

On 17 October 2007, the pilot of a Cessna Aircraft Company C210M, registered VH-WXC, was fatally injured when his aircraft impacted terrain about 257 km south-west of Warburton, WA.

The pilot had delivered an item of general freight at Warburton and was returning to Kalgoorlie when the accident occurred. The aircraft was being operated at night under the visual flight rules.